Conversion Factors

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Energy units

Energy is delivered in many different fuels and sources and can be expressed in terms of volume, mass, energy or emissions. Using the below conversion factors, it is possible to express each fuel or energy source in common units of energy or emissions so that they can be compared and aggregated.

Energy unit types

Joule(J): Joule is the international unit of energy

Kilowatt hour (kWh): This is the conventional unit of energy that electricity is measured by and charged for commercially.

Tonne of oil equivalent (toe): This is the conventional standardised unit of energy and is defined on the basis of a tonne of oil having a net calorific value of 41,868 kj/kg. A related unit is the kilogram of oil equivalent (kgoe), where 1 kgoe=103 toe.

Energy conversion factors

To

toe

MWh

GJ

From

Multiply by

toe

1

11.63

41.868

MWh

0.086

1

3.6

GJ

0.02388

0.2778

1

Calorific values

The conversion of a fuel quantity from physical units into energy units requires a conversion factor which expresses the heat obtained from one unit of the fuel. This conversion factor is termed the calorific value or heating value of the fuel.

Fuel

Net Calorific Value toe/t

Net Calorific Value MJ/t

Crude Oil

1.0226

42,814

Gasoline (Petrol)

1.0650

44,589

Kerosene

1.0556

44,196

Jet Kerosene

1.0533

44,100

Gasoil / Diesel

1.0344

43,308

Residual Fuel Oil (heavy oil)

0.9849

41,236

Milled Peat

0.1860

7,787

Sod Peat

0.3130

13,105

Peat Briquettes

0.4430

18,548

Coal

0.6650

27,842

Liquefied Petroleum Gas (LPG)

1.1263

47,156

Petroleum Coke

0.7663

32,084

Conversion Factor

Conversion Factor

Electricity

86 toe/GWh

3.6 TJ/GWh

Emission factors

The table below shows emission factors for CO2 per unit of energy for specific fuels.

Fuel

tCO₂/TJ
(NCV)

g
CO₂/kWh
(NCV)

Liquid Fuels

Motor Spirit (Gasoline)

70.0

251.9

Jet Kerosene

71.4

257.0

Other Kerosene

71.4

257.0

Gas / Diesel / Oil

73.3

263.9

Residual Oil

76.0

273.6

LPG

63.7

229.3

Naphta

73.3

264.0

Petroleum Coke

92.9

334.5

Solid Fuels and Derivatives

Coal

94.6

340.6

Milled Peat

116.7

420.0

Sod Peat

104.0

374.4

Peat Briquettes

98.9

355.9

Natural Gas

56.9

204.7

Electricity (2017)

121.3

436.6

Fuel densities

Conversion from volume (litres) to mass (tonnes) for liquid fuels requires the densities of the liquids, with the most common fuels shown here.

Fuel

Density (in litres/tonnes)

Kerosene

1250

Crude Oil

1067

Gasoline (Petrol)

1325

Diesel / Gasoil

1183

Heavy Fuel Oil

1062

LPG*

1915

Biodiesel

1136

Bioethanol

1250

Pure Plant Oil

1087

*Assumes a mixture of 70% propane & 30% butane by mass

Primary energy conversion factors

Energy consumption can be expressed as total final consumption (TFC) or total primary energy requirement (TPER). TPER accounts for the energy that is consumed and/or lost in transformation, transmission and distribution processes. It is calculated by applying conversion factors, which vary by fuel type, to TFC values. The table below shows the conversion factors for 2018. Historic conversion factors can be downloaded here.